Device and method for the continuous production of tubular structures that are reinforced with a strengthening support

ABSTRACT

An arrangement for continuously making reinforced hose-shaped structures ( 1 ) having: a conveying unit for continuously driving a row of sequential cylindrical mandrels ( 5 ), which are coupled to each other, in a conveying direction (X) and for returning individual mandrels ( 5 ) to the manufacturing start; at least one extrusion unit ( 4 ) for applying a rubber or plastic layer ( 2 ) to the periphery of the mandrels ( 5 ); at least one unit for applying at least one reinforcement layer ( 3 ); a separating device ( 13 ) for cutting the reinforced hose-shaped structures ( 1 ) at the connecting location of mutually adjoining mandrels ( 5 ) and a strip-off device ( 14 ) for stripping off the cut reinforced hose-shaped structures ( 1 ) from the individual mandrels ( 5 ).  
     The mandrels ( 5 ) are rigid and are coupled to each other in such a manner that, in each case, a peripherally-extending cutting zone (S) of a material, which is different to the mandrel ( 5 ), is provided between the abutting surfaces of mutually adjoining mandrels ( 5 ). The arrangement is so aligned that a vulcanization of the reinforced hose-shaped structures ( 1 ) takes place only at after the strip off.

The invention relates to an arrangement for the continuous production ofreinforced, tube-shaped structures having:

-   -   a conveyor apparatus for continuously driving a row of        sequential cylindrical mandrels in a conveying direction and for        guiding back individual mandrels to the manufacturing start with        the mandrels being coupled to each other;    -   at least one extrusion unit for applying a rubber or plastic        layer to the periphery of the mandrels;    -   at least one unit for applying at least one reinforcement layer;    -   a separation device for cutting the reinforced tube-shaped        structures at the connecting locations of mutually adjoining        mandrels; and,    -   a stripping apparatus for stripping off the cut reinforced,        tube-shaped structures from the individual mandrels.

The invention relates further to a method for continuously makingreinforced, tube-shaped structures.

Reinforced tube-shaped structures are especially used as rolling-loberesilient members for air springs in motor vehicles. A rolling-lobeflexible member blank is made of rubber layers and reinforcement layerswhich are tube-shaped and layered one atop the other.

Conventionally, the rolling-lobe resilient member blanks are made inthat cut-out rubber plates and fabric strips are laid one atop the otherand are further processed. This is relatively complex and subject tofaults.

In EP 0 285 726 B1, a method for applying a filament or cord layer atdefined cord angles to a rubber layer is described with the rubber layerbeing extruded onto a mandrel. For this purpose, the mandrel with therubber layer is clamped into a lathe and rotated while a cord let-offring surrounds the mandrel and is moved forward in the longitudinaldirection of the mandrel with the cord let-off ring being fixed withrespect to rotation.

An automated method for making multi-layered hoses or tubes is knownfrom DE 27 50 642 C2 wherein rubber and reinforcement layers are woundon a rotating mandrel supported at a fixed location. A material feedunit is moved in the longitudinal direction along the mandrel. It ishere disadvantageous that this production method is not continuous butis limited to the length of the mandrel. In addition, the thickness andthe angle of the wound rubber and reinforcement layers cannot be appliedwith adequate accuracy needed for rolling-lobe resilient members.

A winding method for the continuous production of hoses is described inDE 1 180 513 wherein the rubber and reinforcement layers are wound on anendless row of mandrels in series one behind the other and driven in anadvancing direction. The hose is vulcanized on the mandrels. Thereafter,the mandrel component pieces are pulled away and are releaseably hookedto the end of the mandrel component piece running into the windingmachine. The precision, which is required for air spring resilientmembers, can disadvantageously not be ensured in the winding method. Inaddition, the mandrels are thermally loaded during vulcanization and thedanger is present that the mandrels can deform so that a uniform qualityof the rolling-lobe resilient member blanks can no longer be ensured.

A method and an arrangement for manufacturing curved rubber hoses isdescribed in DE 25 45 058 C3 wherein rubber and reinforcement layers areapplied continuously on mandrels driven in a conveying direction with atleast one extruder and one cord reinforcing machine. The mandrels abutdirectly and seamlessly one against the other. In a cutting apparatus,two mandrels are so displaced with respect to each other that a gaparises between their end faces wherein a cutting knife of the cuttingapparatus can engage. Here it is disadvantageous that the filament orcord layers are stretched in the hose blank and are displaced in theirpositions. The mandrels are flexible and are brought into a curvedposition together with the hose or tubular-shaped blank piece, which isdisposed on the mandrel, and are vulcanized in a vulcanization facility.The vulcanized curved hose is subsequently separated from the mandrel.

With the use of flexible mandrels, the accuracy of the rolling-loberesilient member blanks, which is required for air springs, cannot beguaranteed. In addition, during the vulcanization of the rolling-loberesilient member blank on the mandrel, the danger is present that themandrel deforms. In addition, the manufacture of conical rolling-loberesilient members is not possible.

It was therefore an object of the invention to provide an improvedarrangement and a method for the continuous manufacture of reinforcedhose-shaped structures which ensure an adequate manufacturing precisionand high process reliability.

The object is achieved with the arrangement in that: the mandrels arerigid; the mandrels are coupled one to the other so that, in each case,a peripheral cutting zone is provided by a material different from thatof the mandrel; and, that the arrangement is so aligned that thevulcanization of the reinforced hose-shaped structure takes place onlyafter strip off.

In contrast to the method of DE 25 45 058 C3, the extrusion of therubber layers and the spiraling on of the cord layers for generating thereinforcement layers takes place on rigid mandrels driven continuously.A peripherally-extending cutting zone is provided of a materialdifferent to that of the mandrels between the abutting surfaces of themutually coupled mandrels so that a cutting knife can be applieddirectly without the mandrels having to be shifted against each otherand the layers and angles of the reinforcement layers being influencedthereby. For the reliability of the reinforced hose-shaped structures,especially for use in air springs, a defined angle of the cord layers ofthe reinforcement layers is decisive. The dimensional accuracy of themandrels is not affected by the thermal process of the vulcanizationbecause the reinforced hose-shaped structures are stripped in advance ofthe vulcanization from the individual mandrels. In this way, a uniformmanufacturing quality is ensured.

Preferably, a separating means application device for providingseparating means is provided on the periphery of the mandrels. Theseparating means application device is arranged ahead of the firstextrusion unit as seen in the conveying direction. With the appliedseparating means, it is ensured that the reinforced hose-shapedstructures can be easily stripped from the individual mandrels after themanufacture.

Furthermore, it is advantageous to provide a cutting device for cuttingthe stripped-off reinforced hose-shaped structures to definedvulcanization lengths. The cutting device is mounted in themanufacturing process ahead of the vulcanization unit.

According to the invention, the stripped-off reinforced hose-shapedstructures are cut once again in advance of the vulcanization. Thecutting device preferably has a cutting head drivable transversely tothe longitudinal axis of the reinforced hose-shaped structures anddrivable relative thereto. The cutting device also has a fixing unit forclamping and fixing the reinforced hose-shaped structures in the cuttingposition.

The extrusion means preferably have a gear pump for supplying theextruded rubber or plastic to an extrusion head.

In this way, a more precise control of the thickness of the rubber orplastic layers is possible.

Furthermore, a measuring device is preferably provided for continuouslymeasuring the advancing speed of the mandrels. A control unit functionsto control the quantity, which is supplied for the application of atleast one rubber or plastic layer, and to control the rotational speedof the at least one bobbin creel unit in dependence upon the advancingspeed in such a manner that a constant thickness of at least the firstrubber or plastic layer and a defined angle of the at least one cordlayer is formed.

Furthermore, preferably a measuring device is provided for continuouslymeasuring the thickness of the first rubber or plastic layer applieddirectly to the mandrels and a control unit is provided for controllingthe rotational speed of the downstream bobbin creels in dependence uponthe measured thickness of the first rubber or plastic layer. The firstextrusion unit thereby forms a control loop together with the downstreambobbin creel so that a constant cord angle is ensured in dependence uponthe applied thickness of the rubber or plastic layer.

Furthermore, preferably process variable measurement means are providedfor measuring the process variables when applying the rubber or plasticlayers and reinforcement layers. A fault marking unit functions to applymarkings to the reinforced hose-shaped structures when the measuredprocess variables exceed or drop below a particular fault toleranceamount. In this way, it can be ensured that defective regions areseparated out during the uninterrupted continuous manufacture.

The mandrels preferably have a length in the range of one to eightmeters and especially preferable is the length of two to four meters.

Mandrel adapters are provided in order to be able to adapt the length ofthe mandrels flexibly to the production requirements. These mandreladapters abut almost seamlessly against an assigned mandrel and arefixedly coupled thereto. In each case, the mandrel adapters have acoupling element for coupling the mandrel adapter to a further mandrelin such a manner that a cutting zone is provided from a material, whichis different from the mandrel, between the mandrel adapter and thefurther mandrel.

The method of the invention for continuously manufacturing reinforcedhose-shaped structures has the steps of:

-   -   (a) applying rubber or plastic layers and reinforcement layers        as a composite on the periphery of a row of cylindrical, rigid        mandrels, which are sequentially coupled one to the other, and        are continuously driven in a conveying direction;    -   (b) cutting the reinforced hose-shaped structures at the        connecting locations of mutually adjoining mandrels; the        mandrels are so coupled to each other that, in each case, a        peripheral cutting zone is provided from a material, which is        different from that of the mandrel, between the mandrels which        abut one another at abutting surfaces;    -   (c) separating the mutually coupled mandrels from each other;    -   (d) stripping the reinforced hose-shaped structures from the        mandrels;    -   (e) returning the mandrels for forming the row of mandrels in        step (a);    -   (f) vulcanizing the stripped-off reinforced hose-shaped        structures or parts thereof.

As a difference to the continuous manufacturing method of DE 25 45 058C3, the method of the invention is executed with rigid mandrels, whichare coupled one to the other, with a peripherally-extending cutting zonefrom a material different to that of the mandrel so that, whenseparating reinforced hose-shaped structures into segments, it is nolonger necessary to pull the mandrels apart. In this way, it is ensuredthat the position of the reinforcement layers is not changed by theseparating operation.

Furthermore, the vulcanization of the reinforced hose-shaped structuresafter stripping off takes place so that the mandrels, which are used formaking the reinforced hose-shaped structures, are not subjected to thethermal vulcanization operation.

Further advantageous embodiments of the method are described in thedependent claims.

The invention will be explained below in greater detail with respect tothe attached drawing.

FIG. 1 shows a schematic block diagram of a manufacturing arrangementfor the continuous production of reinforced hose-shaped structures.

FIG. 1 shows an arrangement of the invention for the continuousmanufacture of reinforced hose-shaped structures 1 which are formed ofseveral rubber or plastic layers (2 a, 2 b) one atop the other andreinforcement layers 3.

For this purpose, the manufacturing arrangement has a first extrusionunit 4 a for applying a first rubber or plastic layer 2 a to theperiphery of cylindrical, rigid mandrels 5 which are continuouslycoupled one to the other and driven by a conveying unit 6 in a conveyingdirection X. The mandrels 5 are passed through the first extrusion unit4 a so that a rubber or plastic hose is made. The thickness of the firstrubber layer 2 a is measured by a measuring unit 7 which is mountedbehind the first extrusion unit 4 a viewed in the conveying direction X.The first extrusion unit 4 a has a gear pump 8 between the extruder andan extrusion head in order to control the supplied rubber or plasticquantity precisely in dependence upon the thickness measured with themeasuring device 7.

Thereafter, a cord or filament layer is applied at a defined filamentangle with a bobbin creel unit 9 which rotates about the mandrels 5.Optionally, additional bobbin creel units 9 can be provided which can,for example, rotate in mutual opposition in order to apply at least oneadditional filament layer, which can be counter-running, as may berequired.

At least one further extrusion unit 4 b is provided in order to apply afurther rubber or plastic layer 2 b.

The advancing speed of the mandrels 5 is continuously measured by ameasuring unit 10. The process variables are supplied to a control unit(open loop and closed loop) 11 and the extrusion units (4 a, 4 b) andthe at least one bobbin creel unit 9 are so open loop controlled and soclosed loop controlled in dependence upon the speed of advancement andat least the thickness of the first rubber or plastic layer 2 a that adefined reinforcement layer 3 is ensured at fixed filament angles and aconstant thickness of the rubber or plastic layers 2 is ensured.Especially the first extrusion unit 4 a and the directly followingbobbin creel unit 9 form a closed control loop because the filamentangles of the filament layer, which is applied to the first rubber orplastic layer 2 a, is dependent upon the thickness of the first rubberor plastic layer 2 a. The filament angles and the thickness of the firstrubber or plastic layer define essential quality features of reinforcedhose-shaped structures, especially for use in air springs.

Process variables (such as angles and quality of filament layers) forthe reinforcement layers 3 as well as the quality and thicknesses of therubber or plastic layers 2 are measured with suitable measuring means.Defective areas are identified with a fault marking unit 12 by applyingmarkings to the reinforced hose-shaped structures 1 when the measuredprocess variables exceed or drop below a particular fault toleranceamount.

Furthermore, a cutting device 13 is provided for cutting the reinforcedhose-shaped structures 1 at the connecting locations of mutuallyadjoining mandrels 5. For this purpose, the cutting device 13 or theoverall system has either suitable means for detecting theperipherally-extending cut zones S between mandrels 5, which are onebehind the other, or the cutting zones S are determined from theadvancement speed. The cutting device 13 can, for example, have aseparating knife extending about the periphery of the reinforcedhose-shaped structures 1.

Thereafter, the mandrels 5 are decoupled from each other and the cutreinforced hose-shaped structures 1 are stripped off or pulled off theparticular mandrel 5 with a strip-off device 14. This takes placepreferably by introducing compressed air into the intermediate spacebetween the peripheral surface of the mandrel 5 and the inner surface ofthe reinforced hose-shaped structure 1. A compressed air wave firstmigrates from the forward end of the reinforced hose-shaped structure 1to the rear end and the mandrel 5 is pressed out by the pressurized airacting on the end face of the mandrel. The mandrels 5 are preferablyclosed at the end faces.

The individual mandrels 5 are then returned by the conveying apparatusto the start of the manufacturing arrangement as sketched by the arrows.In this way, a continuous endless manufacturing process is ensured.

The stripped-off reinforced hose-shaped structures 1 are thereaftersupplied to a cutting device 15 and cut to the defined vulcanizationlengths. Viewed in the manufacturing direction, the cutting device 15 isahead of a downstream vulcanization unit (not shown) for vulcanizing thecut sections of the reinforced hose-shaped structures. The cuttingdevice 15 has a cutting head 16 moveable transversely to thelongitudinal axis.

Preferably, a separating means application device 17 is provided forapplying separating means to the periphery of the mandrels 5. Theseparating means application unit 17, viewed in the conveying directionX, is mounted ahead of the first extrusion unit 4a. With the appliedseparating means, it is ensured that the reinforced hose-shapedstructures 1 can be easily stripped off the individual mandrels 5 aftermanufacture.

1-19. (canceled)
 20. An arrangement for the continuous manufacture ofreinforced hose-shaped structures comprising: a conveying unit forcontinuously advancing a row of sequentially coupled cylindricalmandrels in a conveying direction (X) and for returning individualmandrels to the manufacturing start; at least one extrusion unit forapplying a rubber or plastic layer to the periphery of the mandrels; atleast one unit for applying at least one reinforcement layer; aseparating device for cutting the reinforced hose-shaped structures atthe connecting locations of mutually adjoining mandrels; and a strip-offunit for stripping off the cut reinforced hose-shaped structures fromthe individual mandrels; the mandrels being rigid and so coupled to eachother that, in each case, a peripherally-extending cutting zone (S) isprovided from a material, which is different from that of the mandrel,between the abutting surfaces of mutually adjoining mandrels; and, thatsaid arrangement is so aligned that a vulcanization of the reinforcedhose-shaped structures takes place after the strip off.
 21. Thearrangement of claim 20, further comprising a separating meansapplication unit for applying separating means to the periphery of themandrels; and, the separating means application unit being mounted aheadof the first extrusion unit as seen in the conveying direction.
 22. Thearrangement of claim 21, further comprising a cutting device for cuttingthe stripped-off, reinforced, hose-shaped structures to definedvulcanization lengths; and, the cutting device being mounted in themanufacturing process ahead of a vulcanization unit.
 23. The arrangementof claim 22, wherein the cutting unit has a cutting head which ismoveable transversely to the longitudinal axis of the reinforcedhose-shaped structure and relative thereto.
 24. The arrangement of claim23, wherein the extrusion units, in each case, include a gear pump forconveying the extruded rubber or plastic to an extrusion head.
 25. Thearrangement of claim 20, further comprising at least one measuring unitfor continuously measuring the advancing speed of the mandrels and acontrol unit for controlling the quantity, which is supplied forapplying a rubber or plastic layer, and for controlling the rotationalspeed of the bobbin creel unit in dependence upon the advancing speed insuch a manner that a constant thickness of at least the first rubber orplastic layer and a defined angle of the at least one filament layer ofthe reinforcement layers is formed.
 26. The arrangement of claim 25,further comprising at least one measuring device for continuouslymeasuring the thickness of the first rubber or plastic layer, which isapplied directly to the mandrel; and, a control unit for controlling therotational speed of the bobbin creel of the downstream bobbin creel unitin dependence upon the measured thickness of the first rubber or plasticlayer.
 27. The arrangement of claim 26, further comprising processvariable measurement means for measuring process variables when applyingthe rubber or plastic layers and reinforcement layers and a faultmarking unit for applying markings to the reinforced hose-shapedstructures when the measured process variables exceed or drop below aparticular fault tolerance amount.
 28. The arrangement of claim 27,wherein the mandrels have a length in the range of between one and eightmeters, preferably between two and four meters.
 29. The arrangement ofclaim 27, further comprising mandrel adapters for lengthening thestandard length of the mandrels; the mandrel adapters abutting virtuallyseamlessly against an assigned mandrel and being coupled tightly to themandrel; and, the mandrel adapters having a coupling element forcoupling the mandrel adapter to an additional mandrel with aperipherally-extending cut zone (S) of a material, which is differentfrom that of the mandrel, between the abutting surfaces to an adjoiningmandrel.
 30. A method for the continuous manufacture of reinforcedhose-shaped structures, the method comprising the steps of: (a) applyingrubber or plastic layers and reinforcement layers in composite to theperiphery of a row of cylindrical rigid mandrels, which are coupledsequentially to each other, and are continuously driven in a conveyingdirection (X); (b) cutting the reinforced hose-shaped structures at theconnecting locations of mutually adjoining mandrels; the mandrels beingcoupled to each other in such a manner that, in each case, aperipherally-extending cutting zone (S) of a material, which isdifferent than that of the mandrel, is provided between the abuttingsurfaces of mutually adjoining mandrels; (c) separating the mutuallycoupled mandrels from each other; (d) stripping off the reinforcedhose-shaped structures from the mandrels; (e) returning the mandrels forforming the row of mandrels in step (a); and, (f) vulcanizing thestripped-off reinforced hose-shaped 20 structures or parts thereof. 31.The method of claim 30, comprising the step of applying separating meansin advance of applying a first rubber or plastic layer to the mandrelsin step (a).
 32. The method of claim 30, comprising the further step ofcutting the stripped-off reinforced hose-shaped structures to definedvulcanization lengths in advance of the vulcanization in step (f). 33.The method of claim 32, comprising the further step of extruding rubberor plastic layers, in each case, to the periphery of the cylindricalmandrels and onto the reinforcement layers.
 34. The method of claim 33,comprising the further step of volume-dependently controlling thethickness of the rubber or plastic layers by means of a gear pump whichis mounted between the extruder and the extrusion head of an extrusionunit.
 35. The method of claim 34, comprising the further step ofspiraling on filaments with a rotating bobbin creel for applying areinforcement layer.
 36. The method of claim 35, comprising the furtherstep of continuously measuring the advancing speed of the mandrels andcontrolling the rubber or plastic quantities, which are supplied for theapplication of a rubber or plastic layer, and controlling theapplication of the reinforcement layer in dependence upon the advancingspeed in such a manner that a constant thickness of the rubber ofplastic layers and a defined reinforcement layer is formed.
 37. Themethod of claim 36, comprising the further step of continuouslymeasuring the thickness of the first rubber or plastic layer, which isapplied directly to the mandrel, and controlling the application of thereinforcement layer in dependence upon the measured thickness of therubber or plastic layer.
 38. The method of claim 39, comprising thefurther step of measuring process variables during the application ofthe rubber or plastic layers and reinforcement layers; marking ofdefective areas of the structures when the process variables exceed ordrop below a particular fault tolerance amount; optical detection of themarked defective areas and separating out the sections of the reinforcedhose-shaped structures, which have been detected as defective, after thestrip off of the reinforced hose-shaped structure.